1. Field of the Invention
The invention relates to pop-up campers pulled on trailers or directly mounted in trucks. More specifically, the invention involves the mounting of a roof on the telescopic support posts of a pop-up camper.
2. Description of the Related Art
Pop-up campers are designed as small trailers or truck compartments which in their collapsed form can be transported by hitching the pop-up camper to a vehicle in the case of a trailer, or by securing the camper in the bed of the truck. Such campers are used for recreational camping in a variety of environments ranging from desert heat to sub-freezing conditions. Pop-up campers conventionally include an aluminum and/or wood body which has a floor and interior cabinets, tables, and benches surrounded by tent-like side walls when the roof is raised. When stationary, the pop-up camper may be deployed to provide living quarters for camping enthusiasts. In order to deploy the pop-up camper, the roof must be raised and tent panels extended so that the interior space is completely extended.
Pop-up campers conventionally utilize telescopic support posts as part of a lifting system to support and lift a roof over the camper body. One such telescopic support is disclosed in U.S. Pat. No. 4,299,421, assigned to the assignee of the present invention, the disclosure of which is incorporated by reference herein. To operate properly, the telescopic support posts should be aligned directly with mounting locations on the roof so that the force imparted by the lifting mechanism, e.g. a hand crank or electric motor, is sufficient to raise the posts. When the telescopic support posts are urged straight up, there is little frictional resistance to the extension. However, when the telescopic support posts are urged in a direction which is at an angle relative to their intended path of extension, frictional resistance to the movement of the segments of the post greatly increases the resistance to the lifting mechanism, thus increasing the difficultly in extending the telescopic support posts, and possibly resulting in failure to properly extend or retract the support posts. If the posts move when the roof is extended over the camper body, the tilting of the telescopic support posts actually resists the gravity retraction of the support posts.
While conventionally pop-up camper tops have been made of aluminum and/or wood because of their light weight and generally beneficial structural characteristics, many newer campers are made partially of a polymer material such as ABS plastic. Such polymer material has advantages over aluminum in several respects. While aluminum is permanently disfigured when dented, polymer material is capable of returning to a shape much closer if not identical to its original shape. Such polymer materials share many of the other beneficial structural characteristics of aluminum, but do not suffer from the denting problem. Polymer material provides similar structural rigidity as aluminum, but provide greater flexibility and resiliency to denting. The machinery for fabricating the polymer material roofs may also be less expensive and the total manufacturing time of a polymer material roof is less. Thus, many components of pop-up campers are now being made of suitable polymer materials.
However, polymer material experiences thermal expansion and contraction to a greater extent than aluminum. This material property is problematic if the pop-up camper body is made of different materials than the camper roof. For example, an aluminum camper body may expand significantly less than a polymer formed roof over a temperature swing, which can vary from -40.degree. to 140.degree. in ambient conditions, e.g., one quarter inch (1/4") to one inch (1") depending on the direction of measurement. The mounting locations of the support posts relative to the body may then vary according to the temperature. In the foregoing example, while the posts may have been perfectly aligned at the original temperature, the temperature at the time of deployment may create a misalignment using conventional attaching methods. The one quarter (1/4) to one and one quarter (11/4) inch differential may only be barely noticeable visually, but such a differential may create a critical misalignment and binding of the telescopic lifting system. Further binding of the system when closed may place excessive loads and stresses on the roof, lifter posts, or camper body leading to damage.
What is needed in the art is a mounting system for a pop-up camper roof lifting system which avoids these problems.